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[PATCH v10 3/3] ReindexPartitions() to set indisvalid.. 324+ messages / 2 participants [nested] [flat]
* [PATCH v10 3/3] ReindexPartitions() to set indisvalid.. @ 2020-10-31 04:52 Justin Pryzby <pryzbyj@telsasoft.com> 0 siblings, 0 replies; 324+ messages in thread From: Justin Pryzby @ 2020-10-31 04:52 UTC (permalink / raw) Something like this should probably have been included in a6642b3ae060976b42830b7dc8f29ec190ab05e4 See also 71a05b223, which mentioned the absence of any way to validate an index. --- src/backend/commands/indexcmds.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index f4d49f5bf6..77390f0c1e 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -1608,8 +1608,6 @@ reindex_invalid_child_indexes(Oid indexRelationId) * CIC needs to mark a partitioned index as VALID, which itself * requires setting READY, which is unset for CIC (even though * it's meaningless for an index without storage). - * This must be done only while holding a lock which precludes adding - * partitions. */ CommandCounterIncrement(); index_set_state_flags(indexRelationId, INDEX_CREATE_SET_READY); @@ -1620,9 +1618,6 @@ reindex_invalid_child_indexes(Oid indexRelationId) */ ReindexPartitions(indexRelationId, REINDEXOPT_CONCURRENTLY | REINDEXOPT_SKIPVALID, true); - - CommandCounterIncrement(); - index_set_state_flags(indexRelationId, INDEX_CREATE_SET_VALID); } /* @@ -2924,6 +2919,24 @@ ReindexPartitions(Oid relid, int options, bool isTopLevel) */ ReindexMultipleInternal(partitions, options); + /* + * If indexes exist on all of the partitioned table's children, and we + * just reindexed them, then we know they're valid, and so can mark the + * parent index as valid. + * This handles the case of CREATE INDEX CONCURRENTLY. + * See also: validatePartitionedIndex(). + */ + if (get_rel_relkind(relid) == RELKIND_PARTITIONED_INDEX + && !get_index_isvalid(relid)) + { + Oid tableoid = IndexGetRelation(relid, false); + List *child_tables = find_all_inheritors(tableoid, ShareLock, NULL); + + /* Both lists include their parent relation as well as any intermediate partitioned rels */ + if (list_length(inhoids) == list_length(child_tables)) + index_set_state_flags(relid, INDEX_CREATE_SET_VALID); + } + /* * Clean up working storage --- note we must do this after * StartTransactionCommand, else we might be trying to delete the active -- 2.17.0 --i3lJ51RuaGWuFYNw-- ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 0 siblings, 0 replies; 324+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <jgdr@dalibo.com> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 324+ messages in thread
end of thread, other threads:[~2025-07-15 10:45 UTC | newest] Thread overview: 324+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2020-10-31 04:52 [PATCH v10 3/3] ReindexPartitions() to set indisvalid.. Justin Pryzby <pryzbyj@telsasoft.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <jgdr@dalibo.com>
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